The characteristics of FDM 3D printed parts depend largely on the process used to make them. This paper demonstrates the design of an FDM 3D printing gas-assisted molding printing head, which is used to eliminate the effect of swelling away from the mold and improve the dimensional accuracy.Meanwhile, the high-pressure hot air ow instantly heats and pressurizes the printing surface layer to enhance the interlayer adhesion strength and its mechanical properties. A stable gas lubrication layer can be formed on the inner wall of gas-assisted nozzle to smoothly deposit laments when the gas ow (Q gas ) is set to 1.75 L/min and the gas pressure (P gas ) is set to 0.4 MPa. The interlayer adhesion strength of the printed parts is enhanced by more than 50% compared with that without gas assistance, and the volumetric shrinkage rate of the optimal group is only 0.13%. The proposed printing method can signi cantly improve the performance of thermoplastic parts and provide new capabilities for biomedical printing, automotive, aerospace and functional device printing in the future.

The characteristics of FDM 3D printed parts depend largely on the process used to make them. This paper demonstrates the design of an FDM 3D printing gas-assisted molding printing head, which is used to eliminate the effect of swelling away from the mold and improve the dimensional accuracy. Meanwhile, the high-pressure hot airflow instantly heats and pressurizes the printing surface layer to enhance the interlayer adhesion strength and its mechanical properties. A stable gas lubrication layer can be formed on the inner wall of gas-assisted nozzle to smoothly deposit filaments when the gas flow (Qgas) is set to 1.75 L/min and the gas pressure (Pgas) is set to 0.4 MPa. The interlayer adhesion strength of the printed parts is enhanced by more than 50% compared with that without gas assistance, and the volumetric shrinkage rate of the optimal group is only 0.13%. The proposed printing method can significantly improve the performance of thermoplastic parts and provide new capabilities for biomedical printing, automotive, aerospace and functional device printing in the future.

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